21 Lecture Outline.ppt52

8/17/2019 21 Lecture Outline.ppt52

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General physics II: Electromagnetism

By Jumar Cadondon


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Course Outline and Description

Course name: PHYSICS 52

Course unit:

Schedule:2:!"#:!! $%h

Consultation hours:$%h &:!!"2:!!

%' &!:!!"&2:!!

% :!!"#:!!

%h (:!!"&!:!!


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How to pass this course?

%H)EE *+,G E-.$S

'I,.* E-.$ /%he 'E cancels out the lo0estscore in any o1 the three long eams i1 possi3le4

P)+B*E$ SE%S B+.)6 7+)8S

B+,9S P+I,%S

Passing Score: !;


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Course Syllabus

.< Electrostatics

&< Electric Charge

2< Coulom3=s *a0

< Electric 'ield

#< Electric Potential 6i11erence > Electric Potential

5< Electric Potential Energy

< Capacitors

a4 Capacitance

34 Parallel"Plate Capacitor

c4 Capacitors in Series and in Parallel

d4 Energy Stored in a Capacitor

e4 6ielectics

""""""""""""""""""""""""""""""""""'I)S% *+,G E-.$I,.%I+,""""""""""""""""""""""""""""""""""


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Course Syllabus

B< $o?ing Charges

&< Electric Current

2< )esisti?ity and )esistance

< +hm=s *a0

#< E$'@ %P6@ and Internal )esistance

5< 7orA@ Energy and Po0er

< Conser?ation Principle

C< 6irect Current Circuits

&< )esistors in Series and in Parallel

2< Circuits Containing Purely )esistors: 8ircho11=s )ules

< )"C Series Circuit

"""""""""""""""""""""""""""""""""SEC+,6 *+,G


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Course Syllabus

.< Concept o1 $agnetic 'ield

B< $agnetic Induction

C< $agnetic 'orce

• On Moving Charges On Electric Currents

6< $agnetic 'ield o1 Electric Currents

• Straight Current Circular Current Solenoid Toroid

E< 'orce Bet0een Parallel Currents

'< Electromagnetic Induction

• Faraday’s Law Lenz’s Law InductanceMagnetic Energy

• R-L Series Circuit

""""""""""""""""""""""""""""""""%HI)6 *+,G E-.$I,.%I+,"""""""""""""""""""""""""""


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References

Ser0ay@ )aymond .< and uille Chris< 2!&2<

College Physics.

th

Edition< Boston: *achinaPu3lishing Ser?ices

Young@ Hugh 6< and 'reedman@ )oger .< 2!&<

Sears and Zemansky’s University Physicswith Modern Physics. &2th Edition< ,e0 YorA:

Pearson $adison 7easley Pu3lishing

Company


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Po0erPointD *ectures 1or

University Physics, Thirteenth Edition

– Hugh D. Young and Roger A. Freedman

Lectures by Wayne Anderson

Coyright ! "earson Education Inc# $ Modi%ied &y Scott 'ildreth $ Cha&ot College ()*+

Chapter 21

Electric Charge andElectric Field

)e?ised 3y Jumar G< Cadondon


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Introduction

• ,ater a.es li%e ossi&le

as a solvent %or &iologicalolecules# ,hat electrical roerties allow it to dothis/

• ,e now &egin our study o%electromagnetism0 one o%the %our %undaental

%orces in 1ature#• ,e start with electric

charge and electric %ields#


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Goals for Chapter !

2 Study electric char"e 3 charge conservation

2 Learn how o&4ects &ecoe charged

2 Calculate electric %orce &etween o&4ects usingCoulo#b$s law

2 Learn distinction &etween electric %orce andelectric field


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Goals for Chapter !

2 Calculate the electric %ield due to any charges

2 5isualize and interret electric %ields

2 Calculate the roerties o% electric dioles


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%lectric Char"e


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%lectric char"e

• Two positi&e or twone"ati&e charges reeleach other#

6 ositive charge and anegative charge attracteach other#

• Chec. out7

htt788www#youtu&e#co8watch/v9:;66Il


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%lectric char"e


6 ositive charge and anegative charge attracteach other#


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%lectric char"e


6 ositive charge anda negative chargeattract each other#

•

Chec. out >alloons in"hET siulations

http://phet.colorado.edu/en/simulation/balloonshttp://phet.colorado.edu/en/simulation/balloons


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Laser printer

• 6 laser rinter a.es use o% %orces &etween

charged &odies#


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%lectric char"e and the structure of #atter

• The articles o% theato are the negativeelectron0 the ositive

proton0 and theuncharged neutron#


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Ato#s and ions

2 6 neutral ato has the sae nu&er o% rotons as electrons#

2 6 positive ion is an ato with one or ore electrons reoved#6 negative ion has gained one or ore electrons#


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Ato#s and ions


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Conser&ation of char"e

2 The roton and electron have the sae agnitude

charge#

2 The agnitude o% charge o% the electron or roton is anatural unit o% charge# 6ll o&serva&le charge isquantized in this unit#

2 The universal principle of charge conservation statesthat the alge&raic su o% all the electric charges in anyclosed syste is constant#


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Conductors and insulators

2 6 conductor erits theeasy oveent o% chargethrough it#

2 6n insulator does not#


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2 6 conductor erits theeasy oveent o% chargethrough it# 6n insulator

does not#

2 Most etals are goodconductors0 while ost

nonetals are insulators#


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2 6 conductor erits theeasy oveent o% charge

through it# 6n insulator does not#

2 Most etals are good

conductors0 while ostnonetals are insulators#

2 Semiconductors are

interediate in their roerties &etween goodconductors and goodinsulators#


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Char"in" by induction

2 The negative rod is a&le to charge the etal &all without losingany o% its own charge#


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%lectric forces on unchar"ed ob'ects

2 The charge within an insulator can shi%t slightly# 6s a result0 anelectric %orce ?can? &e e@erted uon a neutral o&4ect#


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%lectrostatic paintin"

2 Induced ositive charge on the etal o&4ect attracts thenegatively charged aint drolets# Chec. outhtt788www#youtu&e#co8watch/%eature9endscreen3v9zTw.A>tCc>631R9*

http://www.youtube.com/watch?feature=endscreen&v=zTwkJBtCcBA&NR=1http://www.youtube.com/watch?feature=endscreen&v=zTwkJBtCcBA&NR=1


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Coulo#b$s law ( %lectric )ORC%

2 The agnitude o% electric

%orce &etween two ointcharges is directlyproportional to the roduct o% their charges

and

in&ersely proportional

to the sBuare o% thedistance &etween the#

2 Charge easured in Coulo&sD

https://en.wikipedia.org/wiki/Charles-Augustin_de_Coulombhttps://en.wikipedia.org/wiki/Charles-Augustin_de_Coulomb


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Coulo#b$s law

2 Matheatically7 F = k|q*q(8r (

9 *8:π ε )G|q*q(8r (

2 6 *%C+OR

2 Magnitude

2 Direction

2 Units

C l b$ l


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Coulo#b$s law

2 Matheatically7 F = k|q*q(8r (

9 *8:π ε )G|q*q(8r (

2 . 9 < @ *)


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,easurin" the electric force between point char"es

E@ale (*#* coares theelectric and gravitational%orces#

.n alpha particle has mass m


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)orce between char"es alon" a line

• E@ale (*#( %or two charges7

%0o point charges@ F& 25nC@ and F2 "(5 nC@

separated 3y r


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)orce between char"es alon" a line

• E@ale (*#H %or three charges7

%0o point charges@ F& &

F2 "


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*ector addition of electric forces

• E@ale (*#: shows that we ust use vector addition whenadding electric %orces#

%0o eFual positi?e charges@ F& F2 2


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* t dditi f l t i f


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* t dditi f l t i f


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%l t i fi ld


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%lectric field

• 6 charged &ody roduces an electric field in the sace around it

%l t i fi ld


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%lectric field

• ,e use a sall test charge q) to %ind out i% an electric %ield is resent#

%l t i fi ld


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%lectric field

• ,e use a sall test charge q) to %ind out i% an electric %ield is resent#

Definition of the electric field


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• E %ields are 5ECTOR %ields $ and solutions to ro&les reBuire agnitude0 direction0 and units#



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• E %ields are 5ECTOR %ields $ and solutions to ro&les reBuire agnitude0 direction0 and units#

%lectric field of a point char"e


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• E %ields %ro ositive charges oint 6,6 %ro the charge

•

E %ields oint in the direction a "OSITI5E test charge wouldoveJ



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• E %ields oint TO,6RKS a negative charge

•

E %ields oint in the direction a "OSITI5E test chargewould oveJ

%lectric field &ector of a point char"e


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%lectric-field &ector of a point char"e

• E@ale (*#+ - the vectornature o% the electric %ield#

• Ste *7 Coordinate Syste#.

• Ste (7 S/%+CH.



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• Ste (7 S.etchJ

• Ste H7 CO,0O1%1+S..

$ E@ 9 .B8r ( cos θG (-x dir)

$ Ey 9 .B8r ( sin θG (! dir)

θ



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• Ste (7 S.etchJ

• Ste H7 CO,0O1%1+S..

$ E@ 9 .B8r ( cos θG i (-x dir)

$ Ey 9 .B8r ( sin θG j (! dir)

• "# $ = -%% &' i % &' j

θ

%lectron in a unifor# field- %2 ! 4


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%lectron in a unifor# field- %2 !34

• ni%or %ield &etween two charged lates

• Electrical ressureD voltageJG %ro &attery

%lectron in a unifor# field- %2 ! 4


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%lectron in a unifor# field- %2 !34

• ,hat is acceleration o% single electron in %ield/

• ,hat seed and NE a%ter *#) c/ 'ow uch tie/

Superposition of electric fields


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• The total electric %ield at a oint is the vector su o% the %ields due toall the charges resent#



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• The total electric %ield at a oint is the vector su o% the %ields dueto all the charges resent#

• For discrete charges7 E 9 Σ .Bi8r iHGr i 9 Σ .Bi8r i(G r i

• For ?continuous charge distri&utions? E 9 .dBi8r i(G r i

• ST6RT &y %inding d" %ro a in%initesial charge dq in an

infinitesimal element of length (ds)* area (d+)* or volume (d,)

• Integrate over all dq in a line0 sur%ace0 or volue#


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Superposition of Infinitesi#al char"e ele#ents5


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Superposition of Infinitesi#al char"e ele#ents5

• Field o% a linear ring o% charge

• ,hat is d in a tiny segent ds/

$ Total Charge P

$ Total length 9 (πa

$ Charge8length 9 λ

$ λ = P8 (πa

• dP 9 λds

a

ds

%2 !36 ( )ield of char"ed line se"#ent


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%2 !36 )ield of char"ed line se"#ent

• Field o% a linear ring o% charge

%2 !3!7 - )ield of a char"ed line se"#ent


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%2 !3!7 )ield of a char"ed line se"#ent

• More challengingJ

•

The oint " is no longer the S6ME distance away %ro everyeleent dsJJ

%23 !3!! ( )ield of dis8 of char"e


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%23 !3!! )ield of dis8 of char"e

• Treat the dis. as suerosition o% ultile rings o%thic.ness dr J

• dP here7 σda 9 σ(πrGdr

)ield of two oppositely char"ed infinite sheets


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)ield of two oppositely char"ed infinite sheets

• Follow E@ale (*#*(#

%lectric field lines


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• 6n electric field line is an iaginary line or curve

whose tangent at any oint is the direction o% the electric%ield vector at that oint# See Figure (*#(Q &elow#G

%lectric field lines of point char"es


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p "

• Electric %ield lines o% a single oint charge and %or two charges o%oosite sign and o% eBual sign#

%lectric dipoles


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ec c d po es

• 6n electric dipole is a air o% oint charges having eBual

&ut oosite sign andsearated &y a distance#

• ,ater olecules %or anelectric diole#

Dipole electric fields


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p

• The total electric %ield at a oint is the vector su o% the %ields due toall the charges resent#

%2 !3!9 - %lectric field of a dipole


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p

• ,hat is E at a distance y %ro a diole searated &y adistance d and diole oent 0 9 BdG/

)orce and tor:ue on a dipole


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: p

6 diole in an electric %ield can rotateJ

The %ield e@erts a torBue on the diole a&out its center#

) 9 B% and τ 9 r @ ) with agnitude d q)"sin( φ )

Ke%ine 9 Bd0 direction p along diole $ to lus

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21 Lecture Outline.ppt52

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